SolidWorks 2010 Bible

Chapter 7: Selecting Features

Lofts and splines are also governed by similar mathematics. You have seen how the two-point

spline and two-profile loft both create a straight-line transition. Next, a third profile is added to the

loft and a third point to the spline, which demonstrates how the math that governs splines and

lofts is also related to bending in elastic materials. Figure 7.10 shows how lofts and splines react

geometrically in the same way that bending a flexible steel rod would react (except that the spline

and the loft do not have a fixed length).

FIGURE 7.10

Splines, lofts, and bending

Three-point spline, no end conditions

End tangency changed

Reacts like a pinned joint

Notice slight bulge,

just like a real rod in bending

With this bit of background, it is time to move forward and talk about a few of the major aspects

of loft features in SolidWorks. It is possible to write a separate book that only discusses modeling

lofts and other complex shapes. This has in fact been done. The SolidWorks Surfacing and Complex

Shape Modeling Bible (Wiley, 2008) covers a wide range of surfacing topics with examples in far

detail. In this single chapter, I do not have the space to cover the topic exhaustively, but coverage

of the major concepts will be enough to point you in the right direction.

The need for surfaces .....................................................................................

In this chapter, I deal exclusively with solid modeling techniques because they are the baseline that

SolidWorks users use most frequently. Surfaces make it easier to discuss complex shape concepts

because surfaces are generally created one face at a time, rather than by using the solid modeling

method that creates as many faces as necessary to enclose a volume.

From the very beginning, the SolidWorks modeling culture has made things easier for users by

taking care of many of the details in the background. This is because solids are built through